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[zh] Remove old file 'connect-applications-service.md'
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---
title: 使用 Service 连接到应用
content_type: concept
weight: 30
---
<!--
reviewers:
- caesarxuchao
- lavalamp
- thockin
title: Connecting Applications with Services
content_type: concept
weight: 30
-->
<!-- overview -->
<!--
## The Kubernetes model for connecting containers
Now that you have a continuously running, replicated application you can expose it on a network.
Kubernetes assumes that pods can communicate with other pods, regardless of which host they land on. Kubernetes gives every pod its own cluster-private IP address, so you do not need to explicitly create links between pods or map container ports to host ports. This means that containers within a Pod can all reach each other's ports on localhost, and all pods in a cluster can see each other without NAT. The rest of this document elaborates on how you can run reliable services on such a networking model.
This guide uses a simple nginx server to demonstrate proof of concept.
-->
## Kubernetes 连接容器的模型 {#the-kubernetes-model-for-connecting-containers}
既然有了一个持续运行、可复制的应用，我们就能够将它暴露到网络上。
Kubernetes 假设 Pod 可与其它 Pod 通信，不管它们在哪个主机上。
Kubernetes 给每一个 Pod 分配一个集群私有 IP 地址，所以没必要在
Pod 与 Pod 之间创建连接或将容器的端口映射到主机端口。
这意味着同一个 Pod 内的所有容器能通过 localhost 上的端口互相连通，集群中的所有 Pod
也不需要通过 NAT 转换就能够互相看到。
本文档的剩余部分详述如何在上述网络模型之上运行可靠的服务。
本指南使用一个简单的 Nginx 服务器来演示概念验证原型。
<!-- body -->
<!--
## Exposing pods to the cluster
We did this in a previous example, but let's do it once again and focus on the networking perspective.
Create an nginx Pod, and note that it has a container port specification:
-->
## 在集群中暴露 Pod {#exposing-pods-to-the-cluster}
我们在之前的示例中已经做过，然而让我们以网络连接的视角再重做一遍。
创建一个 Nginx Pod，注意其中包含一个容器端口的规约：
{{< codenew file="service/networking/run-my-nginx.yaml" >}}
<!--
This makes it accessible from any node in your cluster. Check the nodes the Pod is running on:
-->
这使得可以从集群中任何一个节点来访问它。检查节点，该 Pod 正在运行：
```shell
kubectl apply -f ./run-my-nginx.yaml
kubectl get pods -l run=my-nginx -o wide
```
```
NAME READY STATUS RESTARTS AGE IP NODE
my-nginx-3800858182-jr4a2 1/1 Running 0 13s 10.244.3.4 kubernetes-minion-905m
my-nginx-3800858182-kna2y 1/1 Running 0 13s 10.244.2.5 kubernetes-minion-ljyd
```
<!--
Check your pods' IPs:
-->
检查 Pod 的 IP 地址：
```shell
kubectl get pods -l run=my-nginx -o custom-columns=POD_IP:.status.podIPs
POD_IP
[map[ip:10.244.3.4]]
[map[ip:10.244.2.5]]
```
<!--
You should be able to ssh into any node in your cluster and use a tool such as `curl` to make queries against both IPs. Note that the containers are *not* using port 80 on the node, nor are there any special NAT rules to route traffic to the pod. This means you can run multiple nginx pods on the same node all using the same `containerPort`, and access them from any other pod or node in your cluster using the assigned IP address for the Service. If you want to arrange for a specific port on the host Node to be forwarded to backing Pods, you can - but the networking model should mean that you do not need to do so.
You can read more about the [Kubernetes Networking Model](/docs/concepts/cluster-administration/networking/#the-kubernetes-network-model) if you're curious.
-->
你应该能够通过 ssh 登录到集群中的任何一个节点上，并使用诸如 `curl` 之类的工具向这两个 IP 地址发出查询请求。
需要注意的是，容器 **不会** 使用该节点上的 80 端口，也不会使用任何特定的 NAT 规则去路由流量到 Pod 上。
这意味着可以在同一个节点上运行多个 Nginx Pod，使用相同的 `containerPort`，并且可以从集群中任何其他的
Pod 或节点上使用 IP 的方式访问到它们。
如果你想的话，你依然可以将宿主节点的某个端口的流量转发到 Pod 中，但是出于网络模型的原因，你不必这么做。
如果对此好奇，请参考 [Kubernetes 网络模型](/zh-cn/docs/concepts/cluster-administration/networking/#the-kubernetes-network-model)。
<!--
## Creating a Service
So we have pods running nginx in a flat, cluster wide, address space. In theory, you could talk to these pods directly, but what happens when a node dies? The pods die with it, and the Deployment will create new ones, with different IPs. This is the problem a Service solves.
A Kubernetes Service is an abstraction which defines a logical set of Pods running somewhere in your cluster, that all provide the same functionality. When created, each Service is assigned a unique IP address (also called clusterIP). This address is tied to the lifespan of the Service, and will not change while the Service is alive. Pods can be configured to talk to the Service, and know that communication to the Service will be automatically load-balanced out to some pod that is a member of the Service.
You can create a Service for your 2 nginx replicas with `kubectl expose`:
-->
## 创建 Service {#creating-a-service}
我们有一组在一个扁平的、集群范围的地址空间中运行 Nginx 服务的 Pod。
理论上，你可以直接连接到这些 Pod，但如果某个节点死掉了会发生什么呢？
Pod 会终止，Deployment 将创建新的 Pod，且使用不同的 IP。这正是 Service 要解决的问题。
Kubernetes Service 是集群中提供相同功能的一组 Pod 的抽象表达。
当每个 Service 创建时，会被分配一个唯一的 IP 地址（也称为 clusterIP）。
这个 IP 地址与 Service 的生命周期绑定在一起，只要 Service 存在，它就不会改变。
可以配置 Pod 使它与 Service 进行通信，Pod 知道与 Service 通信将被自动地负载均衡到该 Service 中的某些 Pod 上。
可以使用 `kubectl expose` 命令为 2个 Nginx 副本创建一个 Service：
```shell
kubectl expose deployment/my-nginx
```
```
service/my-nginx exposed
```
<!--
This is equivalent to `kubectl apply -f` the following yaml:
-->
这等价于使用 `kubectl create -f` 命令及如下的 yaml 文件创建：
{{< codenew file="service/networking/nginx-svc.yaml" >}}
<!--
This specification will create a Service which targets TCP port 80 on any Pod
with the `run: my-nginx` label, and expose it on an abstracted Service port
(`targetPort`: is the port the container accepts traffic on, `port`: is the
abstracted Service port, which can be any port other pods use to access the
Service).
View [Service](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#service-v1-core)
API object to see the list of supported fields in service definition.
Check your Service:
-->
上述规约将创建一个 Service，该 Service 会将所有具有标签 `run: my-nginx` 的 Pod 的 TCP
80 端口暴露到一个抽象的 Service 端口上（`targetPort`：容器接收流量的端口；`port`：可任意取值的抽象的 Service
端口，其他 Pod 通过该端口访问 Service）。
查看 [Service](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#service-v1-core)
API 对象以了解 Service 所能接受的字段列表。
查看你的 Service 资源:
```shell
kubectl get svc my-nginx
```
```
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
my-nginx ClusterIP 10.0.162.149 <none> 80/TCP 21s
```
<!--
As mentioned previously, a Service is backed by a group of Pods. These Pods are
exposed through
{{<glossary_tooltip term_id="endpoint-slice" text="EndpointSlices">}}.
The Service's selector will be evaluated continuously and the results will be POSTed
to an EndpointSlice that is connected to the Service using a
{{< glossary_tooltip text="labels" term_id="label" >}}.
When a Pod dies, it is automatically removed from the EndpointSlices that contain it
as an endpoint. New Pods that match the Service's selector will automatically get added
to an EndpointSlice for that Service.
Check the endpoints, and note that the IPs are the same as the Pods created in
the first step:
-->
正如前面所提到的，一个 Service 由一组 Pod 提供支撑。这些 Pod 通过
{{<glossary_tooltip term_id="endpoint-slice" text="EndpointSlices">}} 暴露出来。
Service Selector 将持续评估，结果被 POST
到使用{{< glossary_tooltip text="标签" term_id="label" >}}与该 Service 连接的一个 EndpointSlice。
当 Pod 终止后，它会自动从包含该 Pod 的 EndpointSlices 中移除。
新的能够匹配上 Service Selector 的 Pod 将自动地被为该 Service 添加到 EndpointSlice 中。
检查 Endpoint，注意到 IP 地址与在第一步创建的 Pod 是相同的。
```shell
kubectl describe svc my-nginx
```
```
Name: my-nginx
Namespace: default
Labels: run=my-nginx
Annotations: <none>
Selector: run=my-nginx
Type: ClusterIP
IP: 10.0.162.149
Port: <unset> 80/TCP
Endpoints: 10.244.2.5:80,10.244.3.4:80
Session Affinity: None
Events: <none>
```
```shell
kubectl get endpointslices -l kubernetes.io/service-name=my-nginx
```
```
NAME ADDRESSTYPE PORTS ENDPOINTS AGE
my-nginx-7vzhx IPv4 80 10.244.2.5,10.244.3.4 21s
```
<!--
You should now be able to curl the nginx Service on `<CLUSTER-IP>:<PORT>` from
any node in your cluster. Note that the Service IP is completely virtual, it
never hits the wire. If you're curious about how this works you can read more
about the [service proxy](/docs/concepts/services-networking/service/#virtual-ips-and-service-proxies).
-->
现在，你应该能够从集群中任意节点上使用 curl 命令向 `<CLUSTER-IP>:<PORT>` 发送请求以访问 Nginx Service。
注意 Service IP 完全是虚拟的，它从来没有走过网络，如果对它如何工作的原理感到好奇，
可以进一步阅读[服务代理](/zh-cn/docs/concepts/services-networking/service/#virtual-ips-and-service-proxies)的内容。
<!--
## Accessing the Service
Kubernetes supports 2 primary modes of finding a Service - environment variables
and DNS. The former works out of the box while the latter requires the
[CoreDNS cluster addon](https://releases.k8s.io/{{< param "fullversion" >}}/cluster/addons/dns/coredns).
-->
## 访问 Service {#accessing-the-service}
Kubernetes支持两种查找服务的主要模式: 环境变量和 DNS。前者开箱即用，而后者则需要
[CoreDNS 集群插件](https://releases.k8s.io/{{< param "fullversion" >}}/cluster/addons/dns/coredns)。
{{< note >}}
<!--
If the service environment variables are not desired (because possible clashing with expected program ones,
too many variables to process, only using DNS, etc) you can disable this mode by setting the `enableServiceLinks`
flag to `false` on the [pod spec](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#pod-v1-core).
-->
如果不需要服务环境变量（因为可能与预期的程序冲突，可能要处理的变量太多，或者仅使用DNS等），则可以通过在
[pod spec](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#pod-v1-core)
上将 `enableServiceLinks` 标志设置为 `false` 来禁用此模式。
{{< /note >}}
<!--
### Environment Variables
When a Pod runs on a Node, the kubelet adds a set of environment variables for
each active Service. This introduces an ordering problem. To see why, inspect
the environment of your running nginx Pods (your Pod name will be different):
-->
### 环境变量 {#environment-variables}
当 Pod 在节点上运行时，kubelet 会针对每个活跃的 Service 为 Pod 添加一组环境变量。
这就引入了一个顺序的问题。为解释这个问题，让我们先检查正在运行的 Nginx Pod
的环境变量（你的环境中的 Pod 名称将会与下面示例命令中的不同）：
```shell
kubectl exec my-nginx-3800858182-jr4a2 -- printenv | grep SERVICE
```
```
KUBERNETES_SERVICE_HOST=10.0.0.1
KUBERNETES_SERVICE_PORT=443
KUBERNETES_SERVICE_PORT_HTTPS=443
```
<!--
Note there's no mention of your Service. This is because you created the replicas
before the Service. Another disadvantage of doing this is that the scheduler might
put both Pods on the same machine, which will take your entire Service down if
it dies. We can do this the right way by killing the 2 Pods and waiting for the
Deployment to recreate them. This time around the Service exists *before* the
replicas. This will give you scheduler-level Service spreading of your Pods
(provided all your nodes have equal capacity), as well as the right environment
variables:
-->
能看到环境变量中并没有你创建的 Service 相关的值。这是因为副本的创建先于 Service。
这样做的另一个缺点是，调度器可能会将所有 Pod 部署到同一台机器上，如果该机器宕机则整个 Service 都会离线。
要改正的话，我们可以先终止这 2 个 Pod，然后等待 Deployment 去重新创建它们。
这次 Service 会 **先于** 副本存在。这将实现调度器级别的 Pod 按 Service
分布（假定所有的节点都具有同样的容量），并提供正确的环境变量：
```shell
kubectl scale deployment my-nginx --replicas=0; kubectl scale deployment my-nginx --replicas=2;
kubectl get pods -l run=my-nginx -o wide
```
```
NAME READY STATUS RESTARTS AGE IP NODE
my-nginx-3800858182-e9ihh 1/1 Running 0 5s 10.244.2.7 kubernetes-minion-ljyd
my-nginx-3800858182-j4rm4 1/1 Running 0 5s 10.244.3.8 kubernetes-minion-905m
```
<!--
You may notice that the pods have different names, since they are killed and recreated.
-->
你可能注意到，Pod 具有不同的名称，这是因为它们是被重新创建的。
```shell
kubectl exec my-nginx-3800858182-e9ihh -- printenv | grep SERVICE
```
```
KUBERNETES_SERVICE_PORT=443
MY_NGINX_SERVICE_HOST=10.0.162.149
KUBERNETES_SERVICE_HOST=10.0.0.1
MY_NGINX_SERVICE_PORT=80
KUBERNETES_SERVICE_PORT_HTTPS=443
```
### DNS
<!--
Kubernetes offers a DNS cluster addon Service that automatically assigns dns names to other Services. You can check if it's running on your cluster:
-->
Kubernetes 提供了一个自动为其它 Service 分配 DNS 名字的 DNS 插件 Service。
你可以通过如下命令检查它是否在工作：
```shell
kubectl get services kube-dns --namespace=kube-system
```
```
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kube-dns ClusterIP 10.0.0.10 <none> 53/UDP,53/TCP 8m
```
<!--
The rest of this section will assume you have a Service with a long lived IP
(my-nginx), and a DNS server that has assigned a name to that IP. Here we use the CoreDNS cluster addon (application name `kube-dns`), so you can talk to the Service from any pod in your cluster using standard methods (e.g. `gethostbyname()`). If CoreDNS isn't running, you can enable it referring to the [CoreDNS README](https://github.com/coredns/deployment/tree/master/kubernetes) or [Installing CoreDNS](/docs/tasks/administer-cluster/coredns/#installing-coredns). Let's run another curl application to test this:
-->
本段剩余的内容假设你已经有一个拥有持久 IP 地址的 Service（my-nginx），以及一个为其
IP 分配名称的 DNS 服务器。 这里我们使用 CoreDNS 集群插件（应用名为 `kube-dns`），
所以在集群中的任何 Pod 中，你都可以使用标准方法（例如：`gethostbyname()`）与该 Service 通信。
如果 CoreDNS 没有在运行，你可以参照
[CoreDNS README](https://github.com/coredns/deployment/tree/master/kubernetes)
或者[安装 CoreDNS](/zh-cn/docs/tasks/administer-cluster/coredns/#installing-coredns) 来启用它。
让我们运行另一个 curl 应用来进行测试：
```shell
kubectl run curl --image=radial/busyboxplus:curl -i --tty
```
```
Waiting for pod default/curl-131556218-9fnch to be running, status is Pending, pod ready: false
Hit enter for command prompt
```
<!--
Then, hit enter and run `nslookup my-nginx`:
-->
然后，按回车并执行命令 `nslookup my-nginx`：
```shell
[ root@curl-131556218-9fnch:/ ]$ nslookup my-nginx
Server: 10.0.0.10
Address 1: 10.0.0.10
Name: my-nginx
Address 1: 10.0.162.149
```
<!--
## Securing the Service
Till now we have only accessed the nginx server from within the cluster. Before exposing the Service to the internet, you want to make sure the communication channel is secure. For this, you will need:
* Self signed certificates for https (unless you already have an identity certificate)
* An nginx server configured to use the certificates
* A [secret](/docs/concepts/configuration/secret/) that makes the certificates accessible to pods
You can acquire all these from the [nginx https example](https://github.com/kubernetes/examples/tree/master/staging/https-nginx/). This requires having go and make tools installed. If you don't want to install those, then follow the manual steps later. In short:
-->
## 保护 Service {#securing-the-service}
到现在为止，我们只在集群内部访问了 Nginx 服务器。在将 Service 暴露到因特网之前，我们希望确保通信信道是安全的。
为实现这一目的，需要：
* 用于 HTTPS 的自签名证书（除非已经有了一个身份证书）
* 使用证书配置的 Nginx 服务器
* 使 Pod 可以访问证书的 [Secret](/zh-cn/docs/concepts/configuration/secret/)
你可以从
[Nginx https 示例](https://github.com/kubernetes/examples/tree/master/staging/https-nginx/)获取所有上述内容。
你需要安装 go 和 make 工具。如果你不想安装这些软件，可以按照后文所述的手动执行步骤执行操作。简要过程如下：
```shell
make keys KEY=/tmp/nginx.key CERT=/tmp/nginx.crt
kubectl create secret tls nginxsecret --key /tmp/nginx.key --cert /tmp/nginx.crt
```
```
secret/nginxsecret created
```
```shell
kubectl get secrets
```
```
NAME TYPE DATA AGE
nginxsecret kubernetes.io/tls 2 1m
```
<!--
And also the configmap:
-->
以下是 configmap：
```shell
kubectl create configmap nginxconfigmap --from-file=default.conf
```
```
configmap/nginxconfigmap created
```
```shell
kubectl get configmaps
```
```
NAME DATA AGE
nginxconfigmap 1 114s
```
<!--
Following are the manual steps to follow in case you run into problems running make (on windows for example):
-->
以下是你在运行 make 时遇到问题时要遵循的手动步骤（例如，在 Windows 上）：
```shell
# 创建公钥和相对应的私钥
openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout /d/tmp/nginx.key -out /d/tmp/nginx.crt -subj "/CN=my-nginx/O=my-nginx"
# 对密钥实施 base64 编码
cat /d/tmp/nginx.crt | base64
cat /d/tmp/nginx.key | base64
```
<!--
Use the output from the previous commands to create a yaml file as follows. The base64 encoded value should all be on a single line.
-->
使用前面命令的输出来创建 yaml 文件，如下所示。 base64 编码的值应全部放在一行上。
```yaml
apiVersion: "v1"
kind: "Secret"
metadata:
name: "nginxsecret"
namespace: "default"
type: kubernetes.io/tls
data:
tls.crt: "LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSURIekNDQWdlZ0F3SUJBZ0lKQUp5M3lQK0pzMlpJTUEwR0NTcUdTSWIzRFFFQkJRVUFNQ1l4RVRBUEJnTlYKQkFNVENHNW5hVzU0YzNaak1SRXdEd1lEVlFRS0V3aHVaMmx1ZUhOMll6QWVGdzB4TnpFd01qWXdOekEzTVRKYQpGdzB4T0RFd01qWXdOekEzTVRKYU1DWXhFVEFQQmdOVkJBTVRDRzVuYVc1NGMzWmpNUkV3RHdZRFZRUUtFd2h1CloybHVlSE4yWXpDQ0FTSXdEUVlKS29aSWh2Y05BUUVCQlFBRGdnRVBBRENDQVFvQ2dnRUJBSjFxSU1SOVdWM0IKMlZIQlRMRmtobDRONXljMEJxYUhIQktMSnJMcy8vdzZhU3hRS29GbHlJSU94NGUrMlN5ajBFcndCLzlYTnBwbQppeW1CL3JkRldkOXg5UWhBQUxCZkVaTmNiV3NsTVFVcnhBZW50VWt1dk1vLzgvMHRpbGhjc3paenJEYVJ4NEo5Ci82UVRtVVI3a0ZTWUpOWTVQZkR3cGc3dlVvaDZmZ1Voam92VG42eHNVR0M2QURVODBpNXFlZWhNeVI1N2lmU2YKNHZpaXdIY3hnL3lZR1JBRS9mRTRqakxCdmdONjc2SU90S01rZXV3R0ljNDFhd05tNnNTSzRqYUNGeGpYSnZaZQp2by9kTlEybHhHWCtKT2l3SEhXbXNhdGp4WTRaNVk3R1ZoK0QrWnYvcW1mMFgvbVY0Rmo1NzV3ajFMWVBocWtsCmdhSXZYRyt4U1FVQ0F3RUFBYU5RTUU0d0hRWURWUjBPQkJZRUZPNG9OWkI3YXc1OUlsYkROMzhIYkduYnhFVjcKTUI4R0ExVWRJd1FZTUJhQUZPNG9OWkI3YXc1OUlsYkROMzhIYkduYnhFVjdNQXdHQTFVZEV3UUZNQU1CQWY4dwpEUVlKS29aSWh2Y05BUUVGQlFBRGdnRUJBRVhTMW9FU0lFaXdyMDhWcVA0K2NwTHI3TW5FMTducDBvMm14alFvCjRGb0RvRjdRZnZqeE04Tzd2TjB0clcxb2pGSW0vWDE4ZnZaL3k4ZzVaWG40Vm8zc3hKVmRBcStNZC9jTStzUGEKNmJjTkNUekZqeFpUV0UrKzE5NS9zb2dmOUZ3VDVDK3U2Q3B5N0M3MTZvUXRUakViV05VdEt4cXI0Nk1OZWNCMApwRFhWZmdWQTRadkR4NFo3S2RiZDY5eXM3OVFHYmg5ZW1PZ05NZFlsSUswSGt0ejF5WU4vbVpmK3FqTkJqbWZjCkNnMnlwbGQ0Wi8rUUNQZjl3SkoybFIrY2FnT0R4elBWcGxNSEcybzgvTHFDdnh6elZPUDUxeXdLZEtxaUMwSVEKQ0I5T2wwWW5scE9UNEh1b2hSUzBPOStlMm9KdFZsNUIyczRpbDlhZ3RTVXFxUlU9Ci0tLS0tRU5EIENFUlRJRklDQVRFLS0tLS0K"
tls.key: "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"
```
<!--
Now create the secrets using the file:
-->
现在使用文件创建 Secret：
```shell
kubectl apply -f nginxsecrets.yaml
kubectl get secrets
```
```
NAME TYPE DATA AGE
nginxsecret kubernetes.io/tls 2 1m
```
<!--
Now modify your nginx replicas to start an https server using the certificate in the secret, and the Service, to expose both ports (80 and 443):
-->
现在修改 nginx 副本以启动一个使用 Secret 中的证书的 HTTPS 服务器以及相应的用于暴露其端口（80 和 443）的 Service：
{{< codenew file="service/networking/nginx-secure-app.yaml" >}}
<!--
Noteworthy points about the nginx-secure-app manifest:
- It contains both Deployment and Service specification in the same file.
- The [nginx server](https://github.com/kubernetes/examples/tree/master/staging/https-nginx/default.conf)
serves HTTP traffic on port 80 and HTTPS traffic on 443, and nginx Service
exposes both ports.
- Each container has access to the keys through a volume mounted at `/etc/nginx/ssl`.
This is set up *before* the nginx server is started.
-->
关于 nginx-secure-app 清单，值得注意的几点如下：
- 它将 Deployment 和 Service 的规约放在了同一个文件中。
- [Nginx 服务器](https://github.com/kubernetes/examples/tree/master/staging/https-nginx/default.conf)通过
80 端口处理 HTTP 流量，通过 443 端口处理 HTTPS 流量，而 Nginx Service 则暴露了这两个端口。
- 每个容器能通过挂载在 `/etc/nginx/ssl` 的卷访问秘钥。卷和密钥需要在 Nginx 服务器启动 **之前** 配置好。
```shell
kubectl delete deployments,svc my-nginx; kubectl create -f ./nginx-secure-app.yaml
```
<!--
At this point you can reach the nginx server from any node.
-->
这时，你可以从任何节点访问到 Nginx 服务器。
```shell
kubectl get pods -l run=my-nginx -o custom-columns=POD_IP:.status.podIPs
POD_IP
[map[ip:10.244.3.5]]
```
```shell
node $ curl -k https://10.244.3.5
...
<h1>Welcome to nginx!</h1>
```
<!--
Note how we supplied the `-k` parameter to curl in the last step, this is because we don't know anything about the pods running nginx at certificate generation time,
so we have to tell curl to ignore the CName mismatch. By creating a Service we linked the CName used in the certificate with the actual DNS name used by pods during Service lookup.
Let's test this from a pod (the same secret is being reused for simplicity, the pod only needs nginx.crt to access the Service):
-->
注意最后一步我们是如何提供 `-k` 参数执行 curl 命令的，这是因为在证书生成时，
我们不知道任何关于运行 nginx 的 Pod 的信息，所以不得不在执行 curl 命令时忽略 CName 不匹配的情况。
通过创建 Service，我们连接了在证书中的 CName 与在 Service 查询时被 Pod 使用的实际 DNS 名字。
让我们从一个 Pod 来测试（为了方便，这里使用同一个 Secret，Pod 仅需要使用 nginx.crt 去访问 Service）：
{{< codenew file="service/networking/curlpod.yaml" >}}
```shell
kubectl apply -f ./curlpod.yaml
kubectl get pods -l app=curlpod
```
```
NAME READY STATUS RESTARTS AGE
curl-deployment-1515033274-1410r 1/1 Running 0 1m
```
```shell
kubectl exec curl-deployment-1515033274-1410r -- curl https://my-nginx --cacert /etc/nginx/ssl/tls.crt
...
<title>Welcome to nginx!</title>
...
```
<!--
## Exposing the Service
For some parts of your applications you may want to expose a Service onto an
external IP address. Kubernetes supports two ways of doing this: NodePorts and
LoadBalancers. The Service created in the last section already used `NodePort`,
so your nginx HTTPS replica is ready to serve traffic on the internet if your
node has a public IP.
-->
## 暴露 Service {#exposing-the-service}
对应用的某些部分，你可能希望将 Service 暴露在一个外部 IP 地址上。
Kubernetes 支持两种实现方式：NodePort 和 LoadBalancer。
在上一段创建的 Service 使用了 `NodePort`，因此，如果你的节点有一个公网
IP，那么 Nginx HTTPS 副本已经能够处理因特网上的流量。
```shell
kubectl get svc my-nginx -o yaml | grep nodePort -C 5
```
```
uid: 07191fb3-f61a-11e5-8ae5-42010af00002
spec:
clusterIP: 10.0.162.149
ports:
- name: http
nodePort: 31704
port: 8080
protocol: TCP
targetPort: 80
- name: https
nodePort: 32453
port: 443
protocol: TCP
targetPort: 443
selector:
run: my-nginx
```
```shell
kubectl get nodes -o yaml | grep ExternalIP -C 1
```
```
- address: 104.197.41.11
type: ExternalIP
allocatable:
--
- address: 23.251.152.56
type: ExternalIP
allocatable:
...
$ curl https://<EXTERNAL-IP>:<NODE-PORT> -k
...
<h1>Welcome to nginx!</h1>
```
<!--
Let's now recreate the Service to use a cloud load balancer. Change the `Type` of `my-nginx` Service from `NodePort` to `LoadBalancer`:
-->
让我们重新创建一个 Service 以使用云负载均衡器。
将 `my-nginx` Service 的 `Type` 由 `NodePort` 改成 `LoadBalancer`：
```shell
kubectl edit svc my-nginx
kubectl get svc my-nginx
```
```
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
my-nginx LoadBalancer 10.0.162.149 xx.xxx.xxx.xxx 8080:30163/TCP 21s
```
```
curl https://<EXTERNAL-IP> -k
...
<title>Welcome to nginx!</title>
```
<!--
The IP address in the `EXTERNAL-IP` column is the one that is available on the public internet. The `CLUSTER-IP` is only available inside your
cluster/private cloud network.
Note that on AWS, type `LoadBalancer` creates an ELB, which uses a (long)
hostname, not an IP. It's too long to fit in the standard `kubectl get svc`
output, in fact, so you'll need to do `kubectl describe service my-nginx` to
see it. You'll see something like this:
-->
在 `EXTERNAL-IP` 列中的 IP 地址能在公网上被访问到。`CLUSTER-IP` 只能从集群/私有云网络中访问。
注意，在 AWS 上，类型 `LoadBalancer` 的服务会创建一个 ELB，且 ELB 使用主机名（比较长），而不是 IP。
ELB 的主机名太长以至于不能适配标准 `kubectl get svc` 的输出，所以需要通过执行
`kubectl describe service my-nginx` 命令来查看它。
可以看到类似如下内容：
```shell
kubectl describe service my-nginx
...
LoadBalancer Ingress: a320587ffd19711e5a37606cf4a74574-1142138393.us-east-1.elb.amazonaws.com
...
```
## {{% heading "whatsnext" %}}
<!--
* Learn more about [Using a Service to Access an Application in a Cluster](/docs/tasks/access-application-cluster/service-access-application-cluster/)
* Learn more about [Connecting a Front End to a Back End Using a Service](/docs/tasks/access-application-cluster/connecting-frontend-backend/)
* Learn more about [Creating an External Load Balancer](/docs/tasks/access-application-cluster/create-external-load-balancer/)
-->
* 进一步了解如何[使用 Service 访问集群中的应用](/zh-cn/docs/tasks/access-application-cluster/service-access-application-cluster/)
* 进一步了解如何[使用 Service 将前端连接到后端](/zh-cn/docs/tasks/access-application-cluster/connecting-frontend-backend/)
* 进一步了解如何[创建外部负载均衡器](/zh-cn/docs/tasks/access-application-cluster/create-external-load-balancer/)